Ion docking drives HER carbon-based electrocatalyst performance

Despite tremendous progress in understanding electrocatalysis in carbon electrodes, existing approaches overlook the key role of the electric double layer, which is essential to fully understand the complex nature of electrochemical reactions. The remaining challenge is to develop an electrocatalytic model that fully encompasses all phenomena, in order to capture a more accurate representation of the intricate processes taking place. Here we present a comprehensive experimental approach using carbon electrocatalysts, together with advanced reactive atomistic simulations, to explore the fundamental aspects of the hydrogen evolution reaction. Contrary to the state of knowledge, our findings reveal essential ion effects that govern electrocatalysis. We uncovered dynamic mechanisms where cations dock in the microporosity of carbon electrodes under the effect of an applied negative potential, resulting in a strong polarization of the electrode. This leads to the localization of charge density on the outermost surface of the carbon, resulting in boosted electrocatalytic efficiency. This study establishes fundamental dynamic mechanisms regarding crucial catalytic impact of ion docking in carbon-based electrocatalysis.